1. Field of the Invention
The present invention relates to a manufacturing apparatus of semiconductors, in particularly details to a heat treatment apparatus of substrates to be processed such as glass substrates for liquid crystal display devices (hereinafter a liquid crystal display device is referred to as a "LCD") and silicon wafers (hereinafter a silicon wafer is simply referred to as a "wafer").
2. Description of the Related Art
So far, in implementing heat treatment to substrates to be processed such as LCDs and wafers in the manufacturing process of semiconductors, on a susceptor regulated in advance at a prescribed temperature, the substrates are disposed to be heat-treated by an amount of heat supplied from the susceptor. At this time, due to the heat treatment temperatures at which the substrates are heated, quality and yield of semiconductor products are largely determined. Accordingly, the heat treatment temperatures, in specific, the temperatures of the susceptor must be regulated with great precision. Therefore, a temperature sensor is inserted into the susceptor to regulate, based on temperatures of the susceptor detected by the temperature sensor, on off and output of a heater. Thereby, the temperatures of the susceptor are supervised. As the temperature sensor, a thermocouple temperature sensor using thermocouple is generally used.
However, there are problems of accuracy and durability such that the thermocouple temperature sensor is poor in accuracy and drastically deteriorates due to the heat. Further, the existing thermocouple temperature sensor only indirectly detects the heat treatment temperatures of the substrate through the temperatures of the susceptor. Accordingly, there is an essential problem that the sensor can not directly detect the temperatures of the substrate itself.
To the ends, various propositions have been disclosed. For instance, Japanese Patent Laid-open Application (KOKAI) No. HEI 5-99752 discloses a method for measuring temperatures in which with an infrared radiation thermometer, temperatures of the substrate during transportation by transporting arm are detected. This method, however, detects only the temperatures of the substrate during transportation. Accordingly, there is a problem that this method can not detect the temperatures when heat-treating by the susceptor.
On the other hand, a method for detecting the temperatures of the substrate in a state being disposed to process is disclosed in Japanese Patent Laid-open Application (KOKAI) No. HEI 7-134069. In this method, in the neighborhood of the center of a susceptor, a penetrating hole is vertically bored with respect to a surface of the susceptor. At the lower side of the penetrating hole, a radiation thermometer is disposed to directly detect infrared rays radiated from the substrate. Thereby, the temperatures of the substrate are directly detected.
In this method, however, a tip of the radiation thermometer inserted from between the susceptor and heating lamps disposed thereunder is disposed in the neighborhood of an upper surface of the susceptor. Accordingly, the radiation thermometer has to be bent by an approximately right angle. In the publication of the above invention, a radiation thermometer jacketed in a cylindrical covering pipe is bent by an approximately right angle to use.
However, when the covering pipe is bent, the bent portion becomes thin, or becomes brittle. As a result of this, from this portion, the infrared rays tend to enter the covering pipe. Accordingly, there is a problem that the infrared radiation thermometer tends to gather heat rays generated from other than the substrate, such as infrared rays from heating lamps.